Range and position iff-jjjstait objects



:SEARCH ROOM ,f/f/' (No Mode.) CROSS REFERENCE i y, B* A. Ham.

METHOD 0F FNENG- RANGE AHB PSITIUNB-HISTAYT GBJECTS.

Paentad Snij 9, 1889.

i L LL 515 Unirse STATES BRADLEY ALLAN iISKE, OF THE UNITED STATES NAVYPATENT Garten;

METHOUOF FlNDiNG. RANGE AND POSITlON OF DISTANT OBJECTSA SPECIFICATIONforming part of Letters Patent No. 406,830, dated July 9, 1889. i

origina application nea omni 17,1383, seria No. 288,505. f Y 301.311.

To all whom t may concern,.-

Be it known that I, BRADLEY ALLAN FIsKn, of the United States Navy, haveinvented anew and useful. Improvement in the Method of Finding Range andPosition of Distant Objects, ot' which the following is a.specification. My invention consists in a new method of finding therange and position of a distant object, which depends upon thedeterminaro tion of a fractional portion of a conduct-ingbody bearing inlength a ratio to the angle included between two lines of sightdirect-ed upon said distant object and the measurement ot' th celectrical resistance of said length.

5 The accompanying `drawings are (Ifigure 4 excepted) au electrica:ciz'igrams, not drawn to `scalc,"and symbolically represent theinvention. In Fig. l is shown a llhcat-stone bridge,

in one member c, of which arranged a body zo of conducting material inarc form and a movable arm traversing the same. In Fig. 2 A is shown a-Yfheatstone bridge having arcs Aand movable arms arranged in two members'l a. b. In Fig. 3 is shown al Wheatstone bridge in 'which arcs connectadjacent'members, as-

wlac and l) d, and movable. arms sweeping over 'said arcs are connectedto the battery. Fig. isfa mathematical diagram illustrating the y ymethod 'ci' determining the angle ATC. Fig. U5 shows 'a disposition ofthe range-finder in connection with a galvanometer, and Fig. 6 @the samein connection with a telephone.

' Similar letters of reference indicate like parts. In Fig'. l, leta b c(Z represent the four memy bers of an ordinary Nheatstone bridge, and Vgthe transverse member, in which ccnnected the galvanometer y. A batteryf is also connected to the bridge in the usual way. 4o In the members cand .rl are placed the fixed resistances c and d', and in the member bthe variable resistance b also, as usual. Une wire' from battcryf,however, connects to the end et inc-mbe .'f, and also to tho pivot Z ofa ,winging arm The extremity ,7: of arm e' moves over and maintaii'iselectrical con+aet with an are h of conducting material, wnic..L ha;3319 @jiji-@fritt- Qrmrufufiuj-fll a: slinviJ m tho mcmbcra of thebridge. It obvious 5o that when the arm lz' is in the position shown infull lines in lfig. l then the current will Divided and this applicationfiled February 27, 188.9 Serial No'.

(Nomodel.) v

traverse the whole arc h, and when said arm is in the position indicatedby dotted lines, Fig. 1, then the arc h will be cut out and the currentwill pass directly tom-emberc.' New 55 assume the arc h to be made ofsuch mate rial and so proportioned that its electrical resistance to acurrent traversing it will be proportional to the length cf arc includedbc.- t tween the conta-ct `end 7e of armzand the conce nccting-point jof member a with said arc. Therefore the resistance interposed in themember ci Aof ,the bridge will be commensurate with the anglej Z ligandif this resistance be known the angle is also known. Let it now beassumed that the galvanlnneter .f/ and ve'iriaoie resistance-vb", lm.iocatett some point distant from the movingfarm fi, from which said armis invisible or inaccessible. Clearly, then, an observer stationed at 7othe galvanomet-er g. and resistance b can, by noting the galvanometerand adjusting the resistance in the usual way, determine the resistanceequilibrating any posit-ion of arm 'i valong the arc 7l, and so discoverthe. angle ot 7 5 adjustment of said arc; or, having adjusted theresistance 1) at some given figure, the observer may, by simply notingthe galvancmeter or any other suitable indicating device, visual oraudible, determine when the arm '11 8o is placed at a desired anglecorresponding to the adjusted resistance, and this indicating device mayobviously be at the place where the moving' arm is located, so that theoperator thcre may thus know when he has placed thc arm at thepredetermined point or at the distant stat-ion, so that the cp'eratorincharge of the resistance b' may know that the arm has been adj ustedproperly; or two indicating devices in the same circuit may give warning9o `to both operators, as above` simultaneously.

Various practical applications et this apparatus will. readily suggestthemselves to those skilled in the art. Thusor example, the elevation ortraining of a gun'may thus be de- 95 tcrmincd or recogni'fed from adistantpoint, the longitudinal axis of the gun corresponding to the arme'.

ifiaf'nrring now tn Fig, "2; 'Tlwill lie apparent that in lien of thevariable resistance b in the toc member l; there is arranged an are hand swinging arm 'i'. The are h is connected at one end j', to theme1nberb,aiid the swinging arm -i makes contact at one end k' with saidare, and to its pivot Z is connected the member d. The arrangement. andconstruction of are 7L vand arm i are similar to that of 'are h and armConsequently'when the arm 'L' is set at a certain point on the 7L thearm i must be set at the corresponding point on the are h', in orderthat theresistance of the lengths ofr the ares h h', respectively,hetivecn the point 7s and point h and pointk and point 'It' may balance;hence it the arm k be set-at a certain an gie the observer at arm k mayrecognize that angle by noting the position of the arm 7c and thegalvanometer, as before. It will be observed,however, thatthe ellect ofmoving the arm i over are h is praetically to lengthen or shorten or tointerpose more or less resistance in the 'member a of the bridge, and byoperating the arm t" a like eieet is produced in the member l). Theresistances or lengths of the members c and d remain unchanged.

Referring now to Fig. 3, therc'is shown an arrangement which forms thebasis ot` the specific embodiment of the invention, more particularlyhereinafter described. In said Fig. 3 the are h is `connected at itsrespective endsj .l to the members 'a c, and the are h' is similarlyconnect-ed at j J to the members b d. The batteryurires connect to thepivots ZZ of the arms t' i", as before. New

' when the arm i is moved from its middle position on its :1 -rc toward7' less resistance is caused in the member o, and more resistance inmember c, and when moved in the opposite direction the reverse occurs.So, also, a similar eltect is produced by moving arm if, and thus theresistance ottercdby all tour members of the bridge may be affectedinstead of that due to only two of them, and differential results may beobtained, as will more fully be apparent in the following description ofa device for measuring distances, such as a range-under for guns. A

Referring to Fig. 4," let T be the position of the object the distanceof which from the point A itis desired to ascertain. Let AB be Y anyshort base-line. Draw AC at right angles to BT, EA parallel to BT, andprolong AT as to D. lly trigonometry y AC=AT sin A'rc i and i AC=AB sinAne, whence AT=AC cosce ATC i ATzAB sin ABU cosce ATC. All, being themeasuredbase-line, is known, and the angle All@ at the point ofobservation .is easily determined, so that the angle ATC remains to befound; but ATCzDAE, and DAE is snbtendcd and measured by the 'are GH.Are GIL-.arc jlb-arc jG, and are jHzar-c J'l; hence Gil--v In lug. 5 thediagrams Figs. 3 and 4 arecombined, fi if, as before, being su-'ingingarms traversing the arcs 7L h', and the connect-ions o; Z7 ed ei' thebridge being present also, as

betere. let the arms 'i' and represent aliclade-arms or telescopes, bothdirected upon the object T. The arcs jG- and jl( not being equal, thebridge will not balance; but when the telescope i is moved to the lineEll then the bridge will balance; but thedistancethus moved is' the areGli, the length ot' which may be read ott from the arc 71 itself. Itwill be seen, therefore, that the operation ot determining the distanceAT heroines, by the aid of this apparatus, exceedingly simple. Theobservers at. the respective telescopes i and 1" direct their lines otsight upon the object.. The observer at z' notes the angle y'AG orlength ot arcjG. lle then moves the telescope 'i until the galvanometerg', which may be placed conveniently near his position, shows nodeflection, and notes the angle jAI-I, or length of arcjll. Thedifference between the arcs jG andjll equals the are GlLwhence the angleATB, and hence the distance AT, is found bythe observer at the arm li,or, in other words, by an observer at the base-line. The disposition ofthe apparatus whereby an observer at a point dist-ant from said baselinemay at once read oit the distance AT from a suitable scale Will' new beexplained.

Referring to Fig. G, the members aand ZJ of the bridge are conneetedtoopposite estremi-4 ties of a bar m In ot conducting'material, and themembers c d are connected to the extremities of a similar and parallelbar o p. Adjustable upon said bars o p and mn is a slider r I7", havinga middle portion .sof insulating inaterial, so that the current from barne fn., for example, does not pass across said slider r r to bar o p,but proceeds bythe wire g through the telephone g, which here takes theplace of the galvanomctcr g in the preceding figures. interposed in thebattery-wire, as at t, is any form of automatic eircnitbieaker orbuzzer, the objcctof which is to produce an audible sound inthetelephone g. y Suppose, now, that the telescopesfi and I1l are sightedupon the distant object T, as before, and thatl the' Slider 'r is at themiddle point l of the parallel bars m n and o p. The resist-ances in thebridge will obviously not balance, and the sound ot the buzzer'will beheard in the telephone g. It has already been explained in connectionwith Fig. 5 how, by moving telescope to the point il, the resistancesmight `be balanced, and it that were done, with the arrangement shown inFig. G, the fact would roo IIO

obviously be indicated by a cessation ot' sound (member if) by thelength ot the arc. GH.'

Similarly the distance on the bridge from 7" to G (member c) isgreatertnan the distance irpin fr to 7.1 (member d) by the length of areLTU..

Nowlet the resistance per unit len gth of the bars m n o y) he madeequal te or with some definite relation lo the resistance per unitlength ol the arcs 71 71 and lay oil' on bar n1 n. a distance Vr 3 andon har o p a distance J" 3, said distances being such that theresistance due thereto will be equal to that, of the arc GH. Clearly, ifthe end 'r of the slider be moved to the position 2 on bar m n, themember a will be increased and the member' b will be diminished by the'distance r 2, which offers a resistance equal to one-half that of areGH, and if the end -r of the slider be moved to the position 2 on bar op then the membere will be decreased and the member (l increased by thedistance i 2, which also has a resistance equal to one-halt ot' areGI-l.- As both ends of the slider move simultaneously, it follows thatwhen its extremities are adjusted in the position 2 then the bridge willbalance and the sound in the telephone will cease. Applying thispractically, let the bars m n.01) be laid. oif in suitablescale-divisions from 7' to nand i to p. The two telescopes 'L' and 'zbein g sighted on the obj ect, the distant observer listens at thetelephone g and moves the slider i' r along the bars m n o p until thesound ceases. The scale marked on the bars then shows an indicationcorresponding to the length of are GH, or, if desired, actual distancescorresponding to such indications.

To illustrate the practical utility of the apparatus, the followinginstances may be given: The telescopes 'i ,suitably mounted upon theirarcs 7ih, are givonto two observers, who proceed to a skirmish-line, orto any `other advanced position, and, select-ing a baseline ofpredetermined length, train their instruments upon any` desired point ofan cnemys works or column. The fact that this is done may be indicatedby any suitable ilag-signal, or by one sent electrically to the rearover the innige-connections. The observer at the telcphone g" maybesupposed to be stationedin proximity to a battery of guns ready to openfire. As soon as the signal is sent that the telescopes are sighted theobserver at the telephone adjusts the slider lr Ir until the sound inthe instrument ceases, and then determines the ran ge from the marks onthe bars 1n. n. o 7) when the guns are laid accordingly. The inventionis, however, especially applicable to use in connection with pneumaticguns for the projection of shells charged with high explosives. y A gunof this type is placed in the bow of a vessel at a certain fixedelevation-forexample, eighteen degrees-and the range of thc projccti leis regulated by varying the air-supply admitted to the gun. lt thusbecomes highly important to determine the distance ot' the' target withall possible accuracy. 'lhe two l elescopes 'i' may be mounted onopposite lsides ofthe vessels upper deck, her breadth of beam, forexample, being,r the known base-line, While the telephone y" may belocated below and convenient to the an'- 65 regulating valve of the gun.The observers on the upperdeclr` train their telescopes on Jdie object,and the observer at the telephone oetermines the dista-nce in the manneralready described, and in accordance with this deterv`` 7o mina-tionadjusts the valve.

The specific apparatus herein set forth, which constitutes one practicalmeans of carrying my invention into eiect to produce beneficial results,is fully described and claimed in an- 75 other application liled by meon the 17th d ay of October, 1888, Serial No. 288,505, of whichapplication this my present application is a division.

l. The improvement in the art o1. finding the range of a distant object,which consists in lirst determining afractional portion of aconducting-body bearing in length a ratio to. the angle included betweentwo lines of sight directed upon a distant object, and, sccond,measuring the electrical resistance oi said length, substantially asdescribed.

2. The method of determining the angle ineluded between two lines ot'sight directed 9o upon a distant objcctmhich consists, first, indirecting 'two al idad earn: s lor-,ated at opposite ends of a base-linelongitudinally in line with said object, the said armsestablishing andmaintaining contact With-similar bodies ot' 95 conducting materialsimilarly disposed with reference to said base-line; second, measuringthe difference between the electrical resist ances of thelengths of saidconducting-bodies included between corresponding extremities roo of theaforesaid bodies and the adjusted positions of the contact-pointsgoverned by said arms, substantially as described.

The niethod'of determiningr the angle included between two lines ofsight directed upon a distant objectm'hich consists in, rst, directingtwo pivoted alidade-arnis located at opposite ends of a base-linelongitudinally in line with said object, the said arms being pivoted atone extremity and having their other i 1o extremities moving over arcsof comlucring material; second, placing one arm parallel to the otherarm, and thereby establishing an electrical balance third, measuring thelength of the arc included between the initial and [i5 final positionsof said lastmcntioned arm, substantially as described.

BRADLEY ALLAN FISE. Witnesses:

PARK BENJAMIN, M. lloscn.

